The invention relates to a spreader clamp for use in automobile body repair to straighten dents and other damage to panels of a motor vehicle and the like.
In automobile body repairing, dents to body panels, fenders and the like can sometimes be straightened by forcing the dented panel outwardly to resume its normal position, using bars, mallets, etc. if there is sufficient room adjacent an inside face of the panel to apply sufficient force. Sometimes an inner panel or other interior structure is spaced closely from a dented outer panel and there is insufficient room to hammer the dented outer panel. In such instances, it is known to use a specific type of body repair spreading tool which can be inserted in the space between the inner and outer panels to apply force to the outer panel. The device has contact pads which can be forced against the inner and outer panels to apply an outwards force to the outer panel to move it to the original or desired position, or to serve as an anvil for hammering against to work the panel as desired. There are various classes of tools to effect the above, and these can be classified as mechanically actuated or hydraulically actuated.
Typical mechanical devices are exemplified in U.S. Pat. No. 2,606,469 (Morgenthaler). In this patent, a pair of hinged arms having pads at outer ends are forced apart by screw threaded members which provide an efficient mechanical advantage. Turning one of the screw threaded members requires a wrench, and this can be awkward to use in a restricted space. Also, as the device is tightened, greater force is required to turn the first threaded member, and this greater force must be resisted by holding the second threaded member which otherwise can twist the device out of alignment, causing the force to be applied in the wrong locations. Additionally, the contact pads are supported generally perpendicularly from behind on short arms subjected generally to compression, which provide little resilience. Consequently, as the metal is worked, forces between the pads decreases rapidly, which necessitates frequent re-adjustment of the screw threaded members to maintain the outwardly directed force. This device can be very time consuming to use.
Devices utilizing hydraulic fluid are shown in U.S. Pat. Nos. 2,588,509 (Forster); 2,447,401 (Ferguson et al) and 2,283,089 (Pfauser) which all use a pair of hinged arms in a scissor-type device. U.S. Pat. No. 4,358,946 (Gallart) generates mechanical forces by using hinged wedges forced apart by a hydraulic ram. While devices of this general type function adequately in some instances, they tend to be heavy and bulky, and some have limited travel. In addition, hydraulic tools tend to be more costly initially than mechanical devices, and there are added complication of increased service cost due to possible hydraulic fluid leakage, etc. Hydraulic devices require either a powered pressurized hydraulic fluid service which can be costly, or individual manual pumping which is commonly a two-handed operation, so that the operator is not free to handle other tools at the same time.
The other devices for assisting in body repair include a dent puller as shown in U.S. Pat. No. 4,116,035 (Malarsky). Several embodiments of this apparatus are shown in which at least two legs engage portions of the body remote from the dent, and a puller rod engages a hole in the dented panel to pull the panel outwardly against a reaction force from the legs. In one embodiment, a pair of adjustable, locking compound hand pliers are used to move the pulling rod in increments, the pliers providing mechanical advantage and locking ability which frees the operator's hands. This device usually requires drilling at least one hole in the dented panel, which aggravates rusting of the panel. U.S. Pat. No. 4,373,373 (Schaefer) discloses an automobile body repair tool which is affixed to one jaw of adjustable compound locking hand pliers which are generally similar to those shown in the patent to Schaefer and provide mechanical advantage for squeezing to deform the material and remaining locked on the panel, which frees the operator's hand. This apparatus is for forming off-set shoulders around an opening in a metal sheet to provide an off-set portion surrounding a cut-out or damaged area to permit application of a patch which would be flush with the original body work.
The patents to Malarsky and Schaefer disclose compound pliers which resemble the well-known lockable and adjustable compound hand pliers as manufactured by Peterson Manufacturing. Co. Inc. of Nebraska, USA, and sold under the registered trademark VISE GRIP. Such pliers are disclosed generally in several U.S. Pat. Nos. for example: 2,280,005 (Petersen); 2,514,130 (Jones) and 4,541,312 (Petersen). These pliers have oppositely facing hinged jaws which can be forced inwardly towards each other under a mechanical advantage by squeezing handle portions together, and then locked in a gripping position to leave the operator's hands free.
To the inventor's knowledge, there are no lightweight, portable and relatively low cost mechanical devices available which can be inserted in a relatively narrow space between two panels, one of which requires forcing outwardly, which can be used to provide a mechanical advantage for forcing the panel outwardly, and to provide locking ability to free the operator's hands for hammering the panel, or for other tasks.